SINGLE-PHASE COMMUTATOR MOTORS 345
with the field strength. A change of distribution of voltage be-
tween the two circuits, in types 6 and 7, with A and C wound
for different voltages, gives the same effect as a change of supply
voltage, and therefore is used for motor control.
195. In those motor types in which a transformation of power
occurs between compensating winding, C, and armature winding,
A, a transformer flux exists in the direction of the brushes, that
is, at right angles to the field flux. In general, therefore, the
single-phase commutator motor contains two magnetic fluxes in
quadrature position with each other, the main flux or field flux,
<i>, in the direction of the axis of the field coils, or at right angles
to the armature brushes, and the quadrature flux, or transformer
flux, or commutating flux, $1, in line with the armature brushes^
or in the direction of the axis of the compensating winding, that
is, at right angles (electrical) with the field flux.
The field flux, <3?, depends upon and is in phase with the field
current, except as far as it is modified by the magnetic action of
the short-circuit current in the armature coil under the commu-
tator brushes.
*In the conductively compensated series motor, 1, the quad-
rature flux is zero at complete compensation, and in the direc-
tion of the armature reaction with undercompensation, in oppo-
sition to the armature reaction at overcompensation, but in
•either case in phase with the current and so approximately with
the field.
In the other motor types, whatever quadrature flux exists is
not in phase with the main flux, but as transformer flux is due
to the resultant m.m.f. of primary and secondary circuit.
In a transformer with non-inductive or nearly non-inductive
secondary circuit, the magnetic flux is nearly 90° in time phase
behind the primary current, a little over 90° ahead of the sec-
ondary current, as shown in transformer diagram, Fig. 166.
In a transformer with inductive secondary, the magnetic flux
is less than 90° behind the primary current, more than 90° ahead
of the secondary current, the more so the higher is the inductivity
of the secondary circuit, as shown by the transformer diagram,
Fig. 166.
Herefrom it follows that:
' In the inductively compensated series motor, 2, the quad-
rature flux is very small and practically negligible, as very little
voltage is consumed in the low impedance of the secondary cir-
cuit, C; whatever flux there is, lags behind the main flux.